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/*
* Copyright (C) 2012, Google Inc. and others
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0 which is available at
* https://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package org.eclipse.jgit.internal.storage.file;
import java.util.Arrays;
import com.googlecode.javaewah.EWAHCompressedBitmap;
/**
* A random access BitSet to supports efficient conversions to
* EWAHCompressedBitmap.
*/
final class BitSet {
private long[] words;
BitSet(int initialCapacity) {
words = new long[block(initialCapacity) + 1];
}
final void clear() {
Arrays.fill(words, 0);
}
final void set(int position) {
int block = block(position);
if (block >= words.length) {
long[] buf = new long[2 * block(position)];
System.arraycopy(words, 0, buf, 0, words.length);
words = buf;
}
words[block] |= mask(position);
}
final void clear(int position) {
int block = block(position);
if (block < words.length)
words[block] &= ~mask(position);
}
final boolean get(int position) {
int block = block(position);
return block < words.length && (words[block] & mask(position)) != 0;
}
final EWAHCompressedBitmap toEWAHCompressedBitmap() {
EWAHCompressedBitmap compressed = new EWAHCompressedBitmap(
words.length);
int runningEmptyWords = 0;
long lastNonEmptyWord = 0;
for (long word : words) {
if (word == 0) {
runningEmptyWords++;
continue;
}
if (lastNonEmptyWord != 0)
compressed.addWord(lastNonEmptyWord);
if (runningEmptyWords > 0) {
compressed.addStreamOfEmptyWords(false, runningEmptyWords);
runningEmptyWords = 0;
}
lastNonEmptyWord = word;
}
int bitsThatMatter = 64 - Long.numberOfLeadingZeros(lastNonEmptyWord);
if (bitsThatMatter > 0)
compressed.addWord(lastNonEmptyWord, bitsThatMatter);
return compressed;
}
private static final int block(int position) {
return position >> 6;
}
private static final long mask(int position) {
return 1L << position;
}
}
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